Well, I want to believe that none of the principles thought here on GC is cast in stone or rock. Everything thought here has a significant measure of flexibility....so the question of whether or not you text/call a girl after only 2mins of having interacted with her shouldn't be viewed and practised with rigid strictness.
For me, I've gathered a tad of experience to know how to make my process work a treat for me. And I'm proud to say that I got those experiences from hundreds and possibly thousands of experimentation with texting and calls, most of them often resulting in painful failures.
My advice is this...
Buff up your fundamentals to a T (it's the foundation of your success), approach as many girls as you possibly can, and no matter what, always try to MAKE A GOOD FIRST IMPRESSION whenever you have the opportunity to. Experiment with the two methods, compare results, and stick with whatever method works the most treat for you. This your learning stage. Utilize it.
The amazing thing about the art of seduction is that, at times, to truly master and appreciate a skill being thought, one has got to experience the same failures, in lesser equal or greater measure, that his dating coach or adviser went through.
For me, there are times when texts undermined my chances, and also times when I appeared so utterly anxious over the phone I could tell the girl could hear,feel and see what a pussy I was. Lol. But that was in the past when I just started out. Things are much better these days....and truth is: I don't have any one specific method I strictly use. I guage the situation and choose whatever method I find apropos for the task, be it texts or calls. Depending on circumstances, I can use, at any time, either of the two.